A medical expert says a three-year-old Reporoa boy was held under water in a spa pool, causing a fatal brain injury

Doctor Patrick Kelly says he believes the 3-year-old suffered child abuse - because his body was found with several broken bones inflicted at different times in the month before his death.

The evidence was presented this week in the Rotorua Coroner's court.

The coroner is tasked with seeking answers into how the young boy died and whether anyone was responsible for his death or earlier injuries.

Travis Mallett has his life support turned off the day after the incident in the spa at his Reporoa home.